The present invention relates to a high pressure collecting chamber with integrated pressure multiplication element.
In fuel injection systems with the use of direct injection internal combustion engines, high pressure collecting chambers (common rails) are utilized. The high pressure collecting chambers serve as a pressure storage for all injectors provided on a direct injection internal combustion engine, to damp pressure pulsations in the fuel injection system. The pulsations are caused on the one hand by the high pressure pump and on the other hand by opening of each injector during the injector phase in the injection system. With increased injection quantities, the pressure in the high pressure injecting chamber (common rail) remains at a high level, so that high pressure can act in the individual injectors of the internal combustion engine.
German patent document DE 197 01 879 A1 discloses a fuel injection device for internal combustion engines. The fuel injector for internal combustion engines disclosed in this reference includes a high pressure collecting chamber (common rail) jointly fillable with fuel by a high pressure pump, which is connected via injection lines with injection valves extending into the combustion chamber of the internal combustion engine to be supplied. The opening and closing movements of the injection valves are controlled each by an electrically-controlled control valve, wherein the control valve can be formed as a 3/2-way valve, which connects a high pressure passage open into an injection opening of the injection valve, with the injection line or a release line. A hydraulic working chamber which is fillable with fuel under high pressure is provided at the control valve member of the control valve. It is controllable for adjusting the adjusted positions of the control valve member in a release passage.
Monosystems which are used in injection systems have the disadvantage that only a small volume is available at the low pressure side for damping pressure pulsations. Thereby pressure vibrations at the low pressure side can act strongly on the total hydraulic system. With low volumes, the pressure pulsations are critical and it is possible that the required high pressure at the beginning of the injection can not be reached.
Accordingly, it is an object of the present invention to provide a high pressure collecting chamber with integrated pressure multiplication element.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a high pressure collecting chamber for receiving a fuel supply under pressure, comprising a piston-shaped pressure multiplication element; means forming a line to a nozzle holder combination such that, via the pressure multiplication element, fuel with high pressure is available in the line; means for pre-stressing the pressure multiplication element; a control chamber through which the pressure multiplication element is integrated; and means limiting the high pressure collecting chamber, the pre-stressed pressure multiplication element which is actuated via the control chamber being integrated in the means forming the high pressure collecting chamber.
With the inventive solution, the action of pressure pulsations is reduced by withdrawing a great a damping volume for reduction of pressure pulsations. Since in the high pressure collecting chamber always a greater fuel quantity is available when compared with that in the individual injector, these volumes can be used as damping volumes for pressure pulsation.
The injector can be integrated in a space-economical way in the high pressure collecting chamber, and at the lower side of the high pressure collecting chamber the surfaces can be provided on which the nozzle holding bodies can be fixed.
Depending on the configuration of the high pressure collecting chamber, by means of the modular principle a change can be provided, with which connecting flanges can be formed for each cylinder no. 4, 6, 8, of which however only a few are utilized when the mounting space for the high pressure collecting chamber is sufficient.
Depending on the design and mounting variants on motor vehicles, identical parts can be utilized and they can be adjusted to individual requirements because of extensions to be mounted. Modifications of the existing systems are not a problem with the use of the modular system.
With the selected solution, the amplitudes of the pressure pulsations can be hold lower at the low pressure side. Further, by an integration of a multiplication piston in the high pressure collecting chamber, valuable space in the region of the cylinder head of an internal combustion engine is saved. The shorter the power lines can be held, the lower the friction forces in the system, the shorter are the response times due to the reduced fluid volumes to be moved.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.